RPi appears to have failed

Got it a few weeks ago, put Debian onto a Transcend card, got it up and running happily using a wireless keyboard/trackpad (mentioned in the Wiki). Was able to connect via RJ45 port too. Also put OpenElec on another SD card and got up and running to a point with that, though it didn't seem to want to know about USB. Put a pre-RC RaspBMC onto another SD card and had similar mixed success. Put it all on one side for a little while. Came back to it today. On booting, got many "New USB device" messages, even when there was nothing in the USB ports, and kernel panic.

PSU is the same as I had running successfully.

Used RaspBMC RC3 and Debian6 19-04-12 (tried a freshly burnt one). Results are the same. ISTM like it could be an issue with the USB port driver. Does anyone have any ideas or has anyone experienced the same thing?

I don't see that it could be a software problem, nor, for that matter, a hardware one other than actual failure. I had it up and running quite happily with the same power supply, keyboard, etc, and the same SD card images, and then it started throwing up mysterious USB errors.

Got a replacement Pi - same results. Tried yet another PSU - same results. Then I swapped the lead from the PSU to the Pi with one from my mobile phone - and it worked flawlessly.

I couldn't understand it until I remembered that when I cased the Pi, I'd had to switch the lead as the one with a solid plastic plug on was a little too big to fit in the case opening, but one with a moulded end did fit. I tried two leads with moulded ends - both had the same problem. So I used a small file to open out the casing hole a little and solved the problem.